The technology disclosed herein generally relates to magnetic resonance (MR) imaging. More specifically, the subject matter relates to estimating a static magnetic (B0) field in MR systems by applying a preparatory radiofrequency (RF) pulse.
In magnetic resonance imaging, the image quality is dependent on the homogeneity of the B0 field. When an object (e.g., a human) is placed inside an MR system, the object's shape, size, magnetic susceptibility, and the like can disrupt the B0 field homogeneity. The B0 field inhomogeneity is often corrected by adjusting the shim coils in the MR systems and/or applying post-processing techniques. However, to correct the B0 field inhomogeneity using shim coils or post-processing techniques, the inhomogeneity of the B0 field needs to be estimated. Currently, image based techniques (e.g., spin echo imaging protocol, gradient imaging protocol, and the like) are used to estimate the B0 field maps. The B0 field maps estimated by such image based techniques are inaccurate since they are confounded by the presence of a plurality of chemical species (e.g., water, fat, bone marrow, cartilage, and the like) in the object.
Thus, there is a need for an enhanced system and method for estimating B0 field maps in MR systems.